<form action="http://127.0.0.1:8870/call-center/cdr-ex/record" method="post">

<textarea name="cdr" id="cdr" rows=70 cols=500>
</textarea>

<input type="button" value="decode" onclick="setUnescapeData();">
<input type="submit">
<script>
function setUnescapeData(){
  document.getElementById("cdr").value = decodeURIComponent(document.getElementById('cdr').value);
}
</script>

</form>